JP2003246157A - Film for thermal stencil printing base paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film for thermal stencil printing base paper which makes both character printing and solid printing clear, which causes no nonuniformity in the thickness of lines of printing, nor nonuniformity in density, wherein wrinkles are hardly brought about in laminating and which is excellent in durability and storage properties. <P>SOLUTION: The film for thermal stencil printing paper is a biaxially oriented polyester film having a thickness of 0.2-7 μm. The melting peak temperature of the film is 180-225°C and the solvent shrinkage stress thereof is 400-1,200 g/mm<SP>2</SP>, while the average air space thickness (Rp) of the film is 3.0-5.5 μm and the average surface roughness thereof is 65-120 nm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film for heat-sensitive stencil printing base paper, and more particularly to a film for heat-sensitive stencil printing base paper which has high printing sensitivity, enables clear printing, and is excellent in durability and storage stability.

[0002]

2. Description of the Related Art In recent years, attention has been paid to heat-sensitive stencil printing using a base paper which is perforated by receiving heat from a xenon flash lamp, a thermal head, or pulse irradiation of a laser beam. The principle of this plate making method is described, for example, in Japanese Examined Patent Publication No. 41-7623 and JP-A-55.
-103957 and Japanese Patent Laid-Open No. 59-143679.

Conventionally, as a base paper used in such heat-sensitive stencil printing, a film obtained by laminating a film for heat-sensitive stencil printing and a porous support with an adhesive or heat is used. As the film for heat-sensitive stencil printing, vinyl chloride, Vinylidene chloride copolymer films, polypropylene films and highly crystallized polyethylene terephthalate films have been used, and thin paper and polyester gauze have been used as the porous support. However, these have the following drawbacks. 1) When a vinyl chloride or vinylidene chloride copolymer film is used, the printed characters do not appear clearly. 2) For polypropylene and polyethylene terephthalate film,
A clear character can be obtained, but solid printing (a symbol or a graphic with a large ink adhesion area) cannot obtain a clear character. 3) In both cases, light and shade appear on the printed part. 4) Partial unevenness of character thickness occurs. 5) Sensitivity is poor and black thin characters, etc. do not appear. 6) When an amorphous polymer such as PET-G is used alone, the perforation diameter becomes too large and the amount of ink consumed is large, and the ink may reach even the white background area where there is originally no ink during printing. There is.

In order to solve these drawbacks, Japanese Patent Laid-Open No. 62-62
Japanese Patent No. 149496 proposes the use of a film having a small crystal melting energy. However, during the process of producing the film, there is a problem in production such as blocking when the polymer chip is dried, adhesion of the vertically stretched film edge to the clip of the tenter type horizontal stretching machine, and the softened polymer at the time of punching in the thermal head. There is a problem in print quality such as easy adherence and streak-like white spots caused by polymer deposits during continuous plate making. In order to solve these problems, for example, Japanese Patent No. 2507612 proposes a film showing two or more melting peaks in DSC temperature rise measurement and is put to practical use. However, in a hardware device for high-speed printing, a heat-sensitive film is used. The sensitivity as a stencil printing base paper may be insufficient. Further, wrinkles may easily occur in the heat-sensitive stencil printing base paper.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks and to provide clear printing of characters and solid printing, no unevenness in thickness of printing, no unevenness in light and shade, and wrinkles during lamination. It is intended to provide a film for heat-sensitive stencil printing base paper which is less likely to cause heat generation and has excellent durability and storability.

[0006]

Means for Solving the Problems That is, the present invention is a biaxially stretched polyester film having a thickness of 0.2 to 7 μm, having a film melting peak temperature of 180 to 225 ° C. and a film solvent shrinkage stress of 400 to 1200 g. / Mm ² and the average air layer thickness (Rp) of the film is 3.0 to
It is a film for heat-sensitive stencil printing base paper, which has a thickness of 5.5 μm and an average surface roughness of 65 to 120 nm.

The film for heat-sensitive stencil printing base paper of the present invention comprises
It is a film used for heat-sensitive stencil printing base paper. The heat-sensitive stencil printing base paper is one which is perforated by receiving heat from a xenon flash lamp, a thermal head, a laser beam or the like, and is a laminate of a heat-sensitive stencil base film and a porous support.

When the film for thermal printing base paper is exposed to flash light or is brought into contact with a thermal head, portions such as characters and images of the printing base paper are perforated.

The process of perforating a film for heat-sensitive stencil printing paper can be divided into the following three steps. 1) Contact with a thermal head or irradiation of electromagnetic waves (xenon flash lamp light, laser pulse, etc.) softens and melts a portion to which thermal energy is applied, which can trigger holes. 2) Heat energy is applied, and the polymer around the trigger of the softened hole is thermally contracted by the diffused heat energy to widen the hole. 3) The softened polymer is attracted to the periphery of the hole by the heat shrinkage force and is solidified by natural cooling and heat radiation, and the hole end is formed, so that the shape of the hole is maintained.

The present invention will be described in detail below.

<Polyester> As the polyester constituting the film for heat-sensitive stencil printing base paper of the present invention, thermoplastic polyester is used. This polyester is composed of a dicarboxylic acid component and a diol component. Examples of the dicarboxylic acid component include phthalic acid, isophthalic acid, 5
-Sodium sulfoisophthalic acid, terephthalic acid, 2-
Potassium sulfoterephthalic acid, 2,7-naphthalenedicarboxylic acid, phenylindanedicarboxylic acid, diphenyletherdicarboxylic acid, oxalic acid, succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, eicosandioic acid, dimer acid, 1 , 4-Cyclohexanedicarboxylic acid, decalin dicarboxylic acid, and hexahydroterephthalic acid can be used. Examples of the diol component include ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2. -Cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, p-xylylene glycol, ethylene oxide adduct of bisphenol A, ethylene oxide adduct of bisphenol sulfone, triethylene glycol, polyethylene oxide glycol , Polytetramethylene oxide glycol and neopentyl glycol can be used.

<Spherical inorganic particles> Polyester contains spherical inorganic particles A and spherical inorganic particles B. They have different average particle sizes and satisfy all of the following conditions (1) to (5). Aspect ratio of spherical inorganic particles A and spherical inorganic particles B: 1.0 to 1.2 (1) Average particle diameter (RA) of spherical inorganic particles A: 0.5 to 2.0 μm (2) Spherical inorganic particles B average particle size (RB): 0.05 to 0.6 μm (3) Particle size ratio of spherical inorganic particles A and spherical inorganic particles B (RA / RB): 2.0 to 20 (4) Spherical inorganic Standard deviation of particle size distribution of particles A and spherical inorganic particles B: less than 0.5 (5) In the formula (1), when the aspect ratio of the spherical inorganic particles A and the spherical inorganic particles B exceeds 1.2, the character It is not preferable because thickness unevenness occurs. The aspect ratio is the major axis / minor axis of the particles.

In the formula (2), if the average particle size (RA) of the spherical inorganic particles A is less than 0.5, the film winding property is deteriorated, and if it exceeds 2.0 μm, the perforation sensitivity is decreased, which is preferable. Absent.

In the formula (3), if the average particle size (RB) of the spherical inorganic particles B is less than 0.05, the film winding property is deteriorated, and if it exceeds 0.6 μm, unevenness in the thickness of characters occurs. It is not preferable.

In the formula (4), when the particle diameter ratio (RA / RB) of the spherical inorganic particles A and the spherical inorganic particles B is less than 2.0, the printing durability is lowered, and when it exceeds 20, the perforation sensitivity is lowered. Is not preferred.

In the formula (5), if the standard deviation of the particle size distribution of the spherical inorganic particles A and the spherical inorganic particles B is 0.5 or more, the size reproducibility at the time of solid printing is lowered, which is not preferable.

<Metal Content> In the present invention, the total amount of the alkali metal element, antimony element and germanium element contained in the polyester is preferably 5 ppm or less, more preferably 3 ppm or less. The total amount of antimony element and germanium element is preferably less than 1 ppm. The amount of the alkali metal element is the p value of each element of Li, Na and K which is quantified by atomic absorption spectrometry.
It is the sum of pm concentrations. The amount of antimony element and the amount of germanium element are quantified by fluorescent X-ray analysis. When the total amount of the alkali metal element, the antimony metal element and the germanium metal element exceeds 5 ppm, the perforation sensitivity is deteriorated, which is not preferable.

As the catalyst used for the polycondensation reaction of polyester, it is preferable to use compounds other than antimony compounds and germanium compounds. Specific examples include calcium compounds, magnesium compounds, and titanium compounds. It is more preferable to use a titanium compound. As the titanium compound, titanium tetrabutoxide,
Titanium acetate is preferred. When a titanium compound is used, the titanium metal element concentration in polyester is preferably in the range of 2 to 50 ppm. When it is less than 2 ppm, the rate of the polycondensation reaction of the polyester is lowered, and a polyester having a predetermined intrinsic viscosity cannot be produced. On the other hand, when it exceeds 50 ppm, the heat resistance of the polyester is lowered, which is not preferable.

The polyester may be obtained by blocking some or all of the terminal hydroxyl groups and / or carboxyl groups with a monofunctional compound such as benzoic acid or methoxypolyalkylene glycol, or, for example, a very small amount of glycerin. , Pentaerythritol and the like, which are modified with a trifunctional or higher functional ester-forming compound within a range where a substantially linear polymer can be obtained.

Among these, the polyesters preferably used in the present invention are poly-2,6-naphthalene dicarboxylate and its copolymers, polyethylene terephthalate and its copolymers, polybutylene terephthalate and its copolymers, and polyhexa. Methylene terephthalate copolymer, polyethylene isophthalate copolymer,
Polybutylene terephthalate copolymers and polyhexamethylene terephthalate copolymers, more preferably polyhexamethylene terephthalate copolymers, polyethylene isophthalate copolymers, polybutylene terephthalate copolymers and polyhexamethylene terephthalate copolymers. To use.

<Melting peak temperature of film> The lowest melting peak temperature (Tm) of the film for heat-sensitive stencil printing base paper of the present invention must be in the range of 180 to 225 ° C. When the film melting peak temperature (Tm) is less than 180 ° C., the polymer softened at the time of perforation easily adheres to the thermal head, and streak-like white spots are generated due to the polymer adhered matter during continuous plate making. Print quality problems occur. In addition, the image tends to have no gradation. Moreover,
Printing durability is reduced. Film melting peak temperature (Tm)
However, if the temperature exceeds 225 ° C, the perforation sensitivity decreases. When this heat-sensitive film has two or more melting peaks, the melting peak on the lowest temperature side is set to Tm, which is 18
It only has to satisfy 0 to 225 ° C. The film melting peak temperature Tm can be adjusted by the blending ratio of polyester and the melt extrusion conditions.

<Solvent shrinkage stress> The solvent shrinkage stress of the film for heat-sensitive stencil printing base paper of the present invention is 400 to 1200 g / m.
m ² is preferably 500 to 1100 g / mm ² , and more preferably 600 to 1050 g / mm ² . If the solvent shrinkage stress is less than 400 g / mm ² , then the probability of perforation will decrease, and if it exceeds 1200 g / mm ² , the storability of the master will decrease.

<Average Air Layer Thickness (Rp)> The average air layer thickness (Rp) of the heat-sensitive stencil printing base paper film of the present invention is 3.
The thickness is 0 to 5.5 μm, preferably 3.5 to 5.5 μm, and more preferably 4.0 to 5.5 μm. 3.0 μm
If less than, the film will stick to the thermal head during plate making,
If it exceeds 5.5 μm, the probability of perforation decreases.

<Average Surface Roughness> The film for heat-sensitive stencil printing base paper of the present invention has an average surface roughness of 65 to 120 nm, preferably 70 to 120 nm, more preferably 75 to 12 nm.
It is 0 nm. When the average surface roughness of the film is less than 65 nm, the slipperiness is low, and wrinkles are likely to occur during sticking with Japanese paper, which is not preferable. If it exceeds 120 nm, the probability of perforation decreases, which is not preferable.

<Others> The heat-sensitive stencil printing base paper film of the present invention may be added with an additive having an absorption peak in the wavelength range of flash light irradiation.

In order to improve the adhesiveness to the porous support, the surface of the film for heat-sensitive stencil printing paper may be subjected to corona discharge treatment in air, carbon dioxide gas or nitrogen gas. A lubricant or a surfactant may be applied or kneaded into the film for heat-sensitive stencil printing base paper, which is preferable because the releasability from the base paper is improved. Further, in order to improve the slipperiness of the film for heat-sensitive stencil printing paper, an organic or inorganic additive may be added.

In the present invention, since the draw ratio is made relatively large, if the average particle size of the added particles is large, breakage easily occurs during film formation. Maximum of additive particles (when multiple kinds of additive particles are present) average particle diameter is 3 μm or less, and further 2 μm
The following is preferable. Further, it is preferable to add a spherical lubricant such as spherical silica particles, and it is preferable that the lubricant has two kinds of sizes having an average particle diameter of 0.5 μm or more, the slip property of the film and the thermal head. It is even more preferable from the viewpoint of sticking to.

<Porous support> As the porous support to be laminated with the film for heat-sensitive stencil printing base paper of the present invention, for example, Japanese paper, Tenpakucho, synthetic fiber paper, various woven fabrics and non-woven fabrics are representative examples. Can be mentioned as. The basis weight of the porous support is not particularly limited, but is usually 2 to 20 g / m.
² , preferably about 5 to 15 g / m ² is used. When a mesh sheet is used, it is 20 to 6
It is preferable to use a woven fiber having a thickness of 0 μm, and it is preferable to use a lattice spacing of 20 to 250 μm.

The adhesive used for bonding the film for heat-sensitive stencil printing paper of the present invention and the porous support is not particularly limited, but vinyl acetate resin, acrylic resin, urethane resin, polyester resin Resin can be mentioned as a typical example.

<Manufacturing Method> Next, a method of manufacturing the film for heat-sensitive stencil printing base paper of the present invention will be described. The film for heat-sensitive stencil printing paper of the present invention, the appropriate amount of the lubricant is added to the resin raw material described above, after sufficiently dried, supplied to the extruder,
It can be produced by melt film-forming from a slit die (for example, T-die) or after melt film-forming by an inflation casting method or the like, and then biaxially stretching. As the biaxial stretching method, for example, sequential biaxial stretching or simultaneous biaxial stretching (stenter method, tube method) can be used. The obtained biaxially stretched film may be appropriately heat treated. In this case, the heat treatment is usually 80 to 200 ° C.
The relaxation rate is 20% or less.

<Film Thickness> The biaxially stretched film for heat-sensitive stencil printing base paper has a thickness of 0.2 to 7 μm, preferably 0.5 to 5 μm, and more preferably 0.8 to 3.5.
μm. If the thickness is less than 0.2 μm, it becomes difficult to bond it to the porous support, the printing is unclear, the uneven density is likely to occur, and the printing durability is deteriorated. When the thickness is more than 7 μm, the sensitivity is low, and a missing portion is generated in printing or the thickness is uneven.

<Heat Shrinkage> In the film for heat-sensitive stencil printing paper of the present invention, the heat shrinkage in the vertical and horizontal directions at 100 ° C. for 10 minutes is the longitudinal heat shrinkage (SMD) and the horizontal heat shrinkage (ST).
Each of D) is preferably 10 to 25%, more preferably 12 to 23%. If the heat shrinkage rate is less than 10%, the plate-making sensitivity of the film is deteriorated, which may cause problems in practical use. If the heat shrinkage rate exceeds 25%, it becomes difficult to maintain the shape of the holes, resulting in excessive ink consumption, which is not preferable. In order to prevent wrinkles and curls from being generated or manifested due to an unexpectedly high temperature (50 ° C or more) during storage of the heat-sensitive stencil printing base paper,
The heat shrinkage at 120 ° C. for 120 minutes is preferably 2% or less.

<Intrinsic Viscosity> The intrinsic viscosity of the heat-sensitive film of the present invention is preferably 0.48 or more and less than 0.85, more preferably 0.58 or more and less than 0.80. If it exceeds 0.85, the viscosity of the film is high, so that it tends to be difficult to crystallize and the shape of perforations is poorly maintained.

<Preservability> When the film for heat-sensitive stencil printing base paper of the present invention is adhered to a porous support, it may be adhered by thermal adhesion or may be attached by an adhesive or the like. As the base paper, it is preferable that the curl of the heat-sensitive stencil printing base paper using the heat-sensitive stencil printing base paper film of the present invention stored at a relatively high temperature of about 60 ° C. is small.

[0035]

EXAMPLES The present invention will be described in more detail with reference to examples. Various physical properties and characteristics in the present invention are measured and defined as follows.

(1) Melting peak temperature of film Tm 10 mg of film was added to TA Instruments T
Using a Thermal Analyst Model 2100, 20 mg of a sample was heated in a N ₂ gas stream at a temperature rising rate of 20 ° C./min to show an endothermic behavior associated with melting of the film.
Analysis is performed by the second derivative, and the point where the value of the first derivative becomes 0 is determined as the melting peak temperature. When the shoulder peak exists in the range of the main melting peak, the shoulder temperature is determined where the slope of the DSC curve is the valley of the first-order differential curve.

(2) Film thickness The thickness t (μm) of the film is the width W (c) of the film.
m), the weight when sampling the length to 1 (cm) is G (g), and the density is d (g / cm ³ ), it is calculated by the following formula. t = 10000G / Wld

(3) The solvent shrinkage stress film is slit into a width of 10 mm and a length of 70 mm, and the average shrinkage stress in the length and width after 5 seconds of immersion in methyl ethyl ketone with a chuck distance of 50 mm is determined.

(4) Average Air Layer Thickness (Rp) The average air layer thickness (Rp) of the film is measured by Microtopography (manufactured by Toyo Seiki Seisaku-sho, Ltd.). That is, light is incident on a glass prism that is brought into close contact with the film at a pressure of 1.5 kg / cm ² , and the average air layer thickness (Rp) in the contact state between the glass prism and the film is calculated by the following equation based on the change in the amount of reflected light. It is a thing.

[0040]

[Equation 1]

(5) Average surface roughness According to the method described in Japanese Industrial Standard JIS B0601, a surface roughness measuring device (SE-3 manufactured by Kosaka Laboratory Ltd.)
The average surface roughness (Ra) was obtained using F). In addition,
The tip radius of the stylus was 2 μm, the load was 30 mg, and the cutoff value was 0.08 mm.

(6) Evaluation of character printing (6-1) Evaluation of clearness of letters and letters JIS 1st level characters are used as a manuscript having a character size of 2.0 mm □ and a porous support made of polyester gauze. "RISO business card pretend" is used as a flash irradiation method, which is pasted with a heat-sensitive film (same for the examples and comparative examples).
Using a plate making / printing machine (made by Riso Kagaku Kogyo Co., Ltd.), a digital printer PRIPO is used as a thermal head punching method.
The plate-making and printing using RT VT-3950 (manufactured by Ricoh Co., Ltd.) is evaluated as follows. In addition,
In the final evaluation, in each of the examples and the comparative examples, the one with the worse evaluation result out of the flash irradiation perforation method and the thermal head perforation method is shown. The evaluation is made with three levels of A, B, and C by the naked eye judgment, A is the same as the manuscript, B is different from the manuscript, but the lines are partially cut or stuck but readable, C is the It is cut or attached to a state where it is almost unreadable.

(6-2) Evaluation of Character Missing The same plate making and printing as in (6-1) are performed to evaluate the missing character of the sentence.

Those having a clearly lacked portion were marked as unusable and indicated by a cross. Also, although it is not completely missing,
A mark indicating slight missing (in a legible range) is indicated by a triangle.

(6-3) Evaluation of Character Thickness Unevenness Using the same plate making and printing machine as in (6-1), a character with a character size of 5.0 mm □ was printed, and the printed state was observed with an internal eye. evaluate. Compared to Bun-u of the manuscript, those with clearly uneven thickness are marked with a bad X and cannot be used, and those without unevenness have a good appearance and are marked with ○ as usable.

(6-4) Evaluation of thickness of Bunyu As in (6-3), plate making and printing are performed, and changes in the thickness of characters are visually evaluated. Compared with the thickness of the characters on the manuscript, those that are clearly thicker or thinner are shown as x, indicating that they cannot be used, and those that have no change in thickness are indicated by a circle. Also, those that are slightly thicker or thinner but can be used are indicated by Δ.

(7) Evaluation of solid printing (7-1) Evaluation of sharpness of solid printing 1 to 5 mmφ (circle filled with black inside)
Using the above as a manuscript, the same plate making and printing as described above are evaluated as follows. The size of the document is used as a reference, and the determination is made based on the unevenness (partial) of the contour. The ones with irregularities of 200 μm or more larger than the size of the original document are marked with poor appearance and are unclear, and are marked with X, and those with irregularities of 50 μm or less are clear and are marked with ◯. The intermediate one is indicated by a triangle. Depending on how you use it, you can also use △.

(7-2) Correspondence with original size of solid printing Printing is performed in the same manner as in (7-1), and all directions (0 ° and 180 °,
45 ° and 225 °, 90 ° and 270 °, 135 ° and 31
(At a position of 5 °), and the correspondence with the size of the document is evaluated. 500 μm compared to original size
Those different from each other (both large and small) are indicated by x as poor correspondence and those by 50 μm or less are indicated by o as good correspondence. The one in the middle is indicated by a triangle, but it can be used depending on the application.

(7-3) Evaluation of dark and light spots of solid printing Printing is performed in the same manner as in (7-1), and it is visually evaluated whether or not there are uneven shades of solid printing. Those with shades are indicated by x, those without are indicated by ◯.

(8) Evaluation of pattern printing Using a checkered pattern in which 6 × 6 1 cm squares as shown in FIG. 1 are used as a document, the same plate-making and printing as described above are evaluated as follows. 4x4 in the center of the printed checkerboard pattern
The size of each square is evaluated, and the correspondence between the size of the original and the size of the original is evaluated. 50 compared to the original size
If there is at least one that differs by 0 μm or more (both large and small), the one with poor compatibility is indicated by X, and the one with 50 μm or less is indicated by O as good compatibility. The one in the middle is indicated by a triangle, but it can be used depending on the application. In addition, when the white background of the checkerboard pattern is stained by the fading of the ink, it is also indicated by a cross.

(9) Evaluation of sensitivity Five types of pencil hardness of 5H, 4H, 3H, 2H and H were prepared, and a character was written with a pressing pressure of 130 g as a manuscript, and the character was read using this manuscript. Evaluate whether it can be done. It is determined that the lightest colored letters written in 5H have the highest sensitivity, and that only the letters written with a darker colored pencil are readable, the lower the sensitivity.

(10) Evaluation of Durability It is expressed by the number of sheets that can be printed before the thermal film is broken by the above-mentioned printing machine (hereinafter referred to as the number of printable sheets). If it is possible to print more than 2000 sheets, it is judged that there is no practical problem as a base paper.

(11) Wrinkle evaluation sample is divided into two, one of which is bonded to a polyester gauze by a usual method. The other one is slit to a width that allows the A4 size to be taken, and both ends are nipped with a tenter roller so that the wrinkles do not enter as much as possible and are carefully bonded to a polyester gauze. The sensitivity evaluations of the two are compared, and if there is a difference, it is determined that the degree of wrinkles is poor. ◎: No difference ○: Difference is 1H or less Δ: Difference is 2H ×: Difference is 3H or more

(12) Evaluation of storability After the laminated base paper was left in a gear oven at 60 ° C. for 2 hours, wrinkles and curls were visually evaluated and judged according to the following criteria. ◯: No change that causes a practical problem before and after leaving. X: A change that causes a practical problem before and after leaving.

Examples 1 to 4 and Comparative Examples 1 to 7 As the thermoplastic polyester, polybutylene terephthalate (abbreviated as PBT) and 2,6-naphthalenecarboxylate having [η] = 0.90 were 5 mol%. Poly (butylene terephthalate / naphthalene carboxylate) copolymer (PBT / 0.8) copolymerized at a ratio of [η] = 0.80
NDC ₅ ), isophthalate 5,30mo
A polybutylene terephthalate / isophthalate copolymer ([abbreviated as PBT / IA ₅ and PBT / IA ₃₀ ]) having [η] = 0.80 copolymerized at a ratio of 1%, and isophthalate 5,10, respectively. , A polyethylene terephthalate / isophthalate copolymer having [η] = 0.65 copolymerized at a rate of 11 mol% (PET / IA ₅ , PET / IA ₁₀ , PET / IA, respectively)
Abbreviated as ₁₁ ), 2,6-naphthalenecarboxylate was copolymerized at a ratio of 10 mol% [η] = 0.64
Polyethylene terephthalate / naphthalene carboxylate copolymer (abbreviated as PET / NDC ₁₀ ) and polyethylene terephthalate (abbreviated as PET) with [η] = 0.65 were used as shown in Table 1.

After sufficiently drying the raw material resin having the composition shown in Table 1, it was fed to the extruder, the resin composition used was melt extruded at the temperature shown in Table 1, and the surface was applied by the electrostatic application casting method. An unstretched film was prepared by cooling and solidifying with a casting drum at a temperature of 20 ° C. This unstretched film,
The film was stretched under the conditions shown in Table 1 and heat-treated for 2 seconds while relaxing by 2% to obtain a film having each thickness.

The biaxially stretched film thus obtained was laminated with polyester gauze (consisting of polyethylene terephthalate fiber) and subjected to a plate making / printing machine for evaluation. The results are shown in Table 2.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

EFFECTS OF THE INVENTION According to the present invention, both character printing and solid printing are clear, there is no unevenness in printing thickness, no unevenness in light and shade, wrinkles do not easily occur during lamination, and durability and storage stability are excellent. An excellent film for heat-sensitive stencil printing base paper can be provided.

The heat-sensitive stencil printing base paper using the film for heat-sensitive stencil printing base paper of the present invention exhibits the following excellent effects. (1) Clear plate making and printing are possible for both text and solid printing. (2) It is possible to perform platemaking and printing without unevenness in thickness and unevenness in light and dark by printing characters and solid printing. (3) The sensitivity is extremely high. And with proper character density,
It has excellent printing durability and an appropriate ink consumption. (4) High sensitivity can be obtained stably without wrinkles. (5) Little curl and excellent storage stability.

[Brief description of drawings]

FIG. 1 is a checkered pattern original in which 6 × 6 1 cm squares are used for evaluation of pattern printing.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinichiro Okada             3-37-19 Oyama, Sagamihara City, Kanagawa Prefecture             People DuPont Films Co., Ltd. Sagamihara Research Center             In the center F-term (reference) 2H114 AB25 BA05 BA10 DA05 DA08                       DA15 DA56 DA73 DA74 DA75                       EA02 FA06                 4F210 AA24 AB17 AC03 AF16 AG01                       AH81 AR06 AR12 QC06 QC07                       QD13 QG01 QG18 QW12

Claims (5)

[Claims] 1. A biaxially stretched polyester film having a thickness of 0.2 to 7 μm, having a film melting peak temperature of 18
0-225 ° C, film solvent shrinkage stress is 400-120
0 g / mm ² and the average air layer thickness (R
p) is 3.0 to 5.5 μm and average surface roughness is 65 to 12
A film for heat-sensitive stencil printing base paper, which has a thickness of 0 nm. 2. The heat-sensitive stencil printing according to claim 1, wherein the polyester contains spherical inorganic particles A and spherical inorganic particles B, which have different average particle diameters and satisfy all of the following conditions (1) to (5). Film for base paper. Aspect ratio of spherical inorganic particles A and spherical inorganic particles B: 1.0 to 1.2 (1) Average particle diameter (RA) of spherical inorganic particles A: 0.5 to 2.0 μm (2) Spherical inorganic particles B average particle size (RB): 0.05 to 0.6 μm (3) Particle size ratio of spherical inorganic particles A and spherical inorganic particles B (RA / RB): 2.0 to 20 (4) Spherical inorganic Standard deviation of particle size distribution of particles A and spherical inorganic particles B: less than 0.5 (5) 3. The film for heat-sensitive stencil printing paper according to claim 1, wherein the total amount of alkali metal element, antimony element and germanium element contained in the polyester is 5 ppm or less. 4. The film for heat-sensitive stencil printing paper according to claim 1, wherein a titanium compound is used as a polycondensation catalyst for polyester, and the titanium metal element concentration in the polyester is 2 to 50 ppm. 5. The method of claim 1 made by simultaneous biaxial stretching.
5. A film for heat-sensitive stencil printing base paper according to any one of 1 to 4.